High capacity fuel pump



A'. C; ALLEN HIGH CAPACITY FUEL PUMP Feb. 1,0, 1959 Filed May 10, 1956 2Sheets-Sheet l www hm @MN WN l!! ver Feb. lo, A .C ALLEN Y HIGH CAPACITYFUEL PUMP Filed May 10, 1956 2 Sheets-Sheet 2 m ff?? United StatesPatent "ice ltilGH CAPA'CH'IY FUEL PUMP Arthur C. Allen, Chicago, lib,assigner to Stewart-Warner Corporation, Chicago, Ill., a corporation ofVirginia Application May 10, 1956, Serial No. 584,093

13 Claims. (Cl. 10S-37) The present invention relates to fuel pumps forcarburetor type internal combustion engines and more particular ly toelectric pumps for supplying fuel to the carburetors of automotivevehicle engines.

Une object of the invention is to provide for maintaining a continuouslyadequate supply of liquid fuel to the carburetor of a high poweredautomotive vehicle engine, for example, an improved electric fuel pump,self-controlled to operate only as necessary to maintain a limited backpressure onrthe pump and having exceptional operating eiciency thatprovides at once for very significant minim'mation of the size andweight of the pump and for strikingly sharp responsiveness of the pumpto only a slight diminution in normal back pressure to pump fuel at ahigh rate sufficient to meet the requirements of even the most powerfulengines used in automotive vehicles.

Another object is to provide an improved pump of the above characterwhich has at once the pumping efiiciency recited in the-previous-o-bject and the capacity to eliciently strain foreign particles fromthe fuel flow through the pump in a manner which maintains the pumpingeiiiciency unimpaired by even substantial accumulations of materialstrained from the fuel.

Another object is to provide for the utmost convenience in servicing theimproved pump recited in the preceding objects.

A more specific object is to provide an improved pump of the characterrecited which has an even output pressure that can be readily adjustedto meet the uid pressure requirements of different carburetors.

A further object is to provide a high capacity, solenoid operated fuelpump which is exceptionally quite in operation.

Other objects and advantages will become apparent from the followingdescription of the exemplaryform of the invention illustrated in thedrawings, in which:

Figure 1 is a longitudinal sectional view of a pump embodying theinvention;

Fig. 2 is a fragmentary plan view showing the fuel inlet portion of thepump body and illustrating diagrammatically the connection of the pumpinlet to a fuel tank;

Fig. 3 is a fragmentary plan view showing the fuel outlet portion of thepump body and illustrating diagrammatically the connection of pumpoutlet to a carburetor;

Fig. 4 is a perspective View showing the pump plunger rotated 90"` withrespect to its position shown in Fig. 1 and partially sectioned toreveal internal valve structure;

Fig. 5 is an internal end view taken from the line 5-5 of Fig. l;

Fig. 6 is a fragmentary detail view taken along the line 6 6 of Fig l;

Fig. 7 is a fragmentary sectional view taken along the line 7-'7 of Fig.l; and

Fig. 8 is a fragmentary plan view showing the control switch cover.

2,872,871 Patented Feb. 1o, 1959 As will presently appear, the structureof the pump embodying the present invention is integrated together in aunique manner which facilitates servicing of the pump by providing quickaccess to any structural component.

In the preferred form shown, the improved pump comprises a hollowelongated body itl molded integrally as a unitary aluminum casting andhaving an outer generally cylindrical shell (also denoted by the numeral10). Convenient support for the pump is provided by a suitable mountingbracket l2 embracing the medial portion of the body lli and adapted forattachment to any suitable vehicle structure (not shown).

The body l0 includes a hollow cylindrical barrel element 14 concentricwith the outer shell of the body and extending to the right, Fig. l, ofthe longitudinal center of the body. Radially spaced inwardly from theouter shell of the 'body itl, the barrel element 14 is supported by anannular web f6 extending radially inward from the outer body shell andmerging with a medial segment of the 'barrel element. v

The pump is energized magnetically by a solenoid assembly 1S removablymounted within the central portion of the body lil. The solenoidassembly 18 encircles a cylindrical plunger guide tube Ztl whichprojects from the inner end of the barrel element i4 nearly to theopposite end of the body l0. The tube 2li is formed from brass or othersuitable nonmagnetic material. The barrel element end of the guide tube20 is flanged radially outward, as shown, and held firmly in a shallowcounterbore 22 in the inner end of the barrel element 14 by an annularseal 24. The seal 2d is backed up by a circular gland 25 pressed intothe counterbore 22 behind the seal.

The solenoid assembly 18 comprises a centrally bored flat disc 23closely encircling the guide tube Ztl and abuttingly engaging the innerend Iof the barrel element i4, Proper orientation of the disc 28 aroundthe tube Ztl is assured by a short locating pin 30 supported in theouter shell of the body lll to extend inwardly into a radial slot 32 inthe periphery of the disc. The disc 28 is formed of magnetic material tobecome one element of a magnetic circuit around the assembly 18.

The outer periphery of the disc 28 lits within one end of a cylindricalinsert 34 lining the outer shell of the body lll) from the disc 28 for asubstantial distance toward the end of the body opposite the barrelelement 14. Formed of magnetic material, the insert 34 provides an outerlongitudinal continuation of the magnetic circuit from the disc 28.

Proper location of the magnetic insert 34 in the body 10 is facilitatedby the locating pin Sil which extends through a short longitudinal slot36 in the adjacent end of the insert.

The space between the insert 3d and the tube 20 forms an annular pocketwhich receives a solenoid .38 prewound on a spool all, dimensioned tohave a close sliding lit around the tube 2li. Two lead wires 42, 44,Fig. 7, extend from the solenoid 38 past the disc 23 to connect with twoterminal sockets 46, 48 attached to the side of the disc 28 opposite thesolenoid.

The solenoid spool 40 is held firmly against the disc Z8 by a springwasher Sil, Fig. l, encircling the tube 20 at the end of the solenoidopposite the disc 28. From an inner peripheral edge which engages thesolenoid spool 40, the spring washer 5t) is dished away from thesolenoid 38 to engage the adjacent surface of a centrally boredretaining nut 52 which lits closely around the outer end of the tubeZtl. The outer periphery of theretainer 52 is threaded into acounterbore 54 formed in the body 10. and extending from the adjacentend of the body somewhat beyond the adjacent end of the insert 34.

A cylindrical gland skirt 60 integral with the outer marginal edge ofthe retainer 52 telescopes around the adjacent end of the insert 34 toabut against an annular seal 62 at the bottom of the counterbore 54.

The retainer 52 is formed from-rnagnetic material to provide acontinuation of the magnetic solenoid circuit extending radially inwardfrom'the adjacent end of the insert 34 to the tube 20. v

The guide tube provides support to a cylindrical pumping plunger 64dimensioned to have a close sliding fit within the tube. Formed ofmagnetic material, the plunger 64 serves as a solenoid core which, uponenergization of the solenoid 38, tends to seek a position along the axisof the solenoid which minimizes the reluctance of the magnetic circuitaround the solenoid. This magnetic circuit extends through the retainerSZ, the insert 34, the disc 28, and the portion of the plunger 64between the disc 28 and the retainer. Thus, upon energization of thesolenoid 38, the plunger is magnetically urged longitudinally totelescope into the retainer 52, as well as into Vthe disc 28, tominimize the overall space and hence the magnetic reluctance between theplunger and the two magnetic elements formed by the disc 28 and theretainer 52.

The end of the tube 20 remote from the barrel element 14 is covered byan intake valve assembly 66 threadedinto an annular boss 68 formed onthe side of the retainer 52 opposite the solenoid 38. The boss 68encircles and extends somewhat beyond the adjacent end of the tube 20.As will presently appear, the intake valve assembly 66 together with theportion of the tube 20 between the valve assembly and the adjacent endof the plunger 64 define a pumping chamber 69 into which fuel isadmitted through the valve assembly.

Structurally, the intake valve assembly 66 comprises a centrally boredgland nut 70 threaded into a counterbore 72 in the boss 68. The innerend of the nut 70 telescopes around the adjacent end of the tube 20 andcompresses an annular seal 74 against the bottom of the counterbore 72,causing the seal to firmly engage the tube.

A counterbore 76 in the outer end of the gland nut 70 receives theradially outward extremities of a spring retaining spider 78. Thecentral portion of the spider 78 is offset, as shown, along the axis ofthe tube 20 toward the plunger 64. The outer ends of the spider 78 areanchored in the counterbore 76 by a centrally bored annulus 80 pressedinto the counterbore behind the spider.

The radially inward marginal edge of the annulus 80 facing the plunger64 provides a seat 82 for a circular check valve disc 84 biased againstvthe valve seat by a compression spring 86 inserted between the valvedisc and the adjacent central portion of the spring retaining spider 78.

Collection of magnetic particles from fuel entering the central bore 88in the annulus 80 is provi-ded for in an extremely simple manner. Forthis purpose a magnetic wire 90, Figs. 1 and 5, is shaped to embrace aboss 92 formed on the annulus 80 to encircle the outer end of the bore88. Opposite ends 94, 96 of the wire 90 are turned into parallel spacedrelation to each other to extend part across the bore 88. The wire 90 ispermanently magnetized so that its opposite ends 94, 96 form pole piecesof opposite polarity which attract magnetic particles fromthe stream offuel entering the bore 88.

The intake valve assembly 66, including the magnetized wire 90, can bedemounted simply by unscrewing the nut 70 from the retainer boss 68.Removal of the intake valve assembly opens up the adjacent end of thetube 20 for convenient withdrawal of the plunger 64, which contains aninternal valve of improved construction that will be describedpresently.

Normally, the plunger 64 is biased away from the intake valve assembly66 to create a substantial gap along the axis of the tube 20 between theinner periphery of the magnetic circuit member 52 and the adjacentend'of the plunger. This biasing action is produced by a helicalcompression spring 98 seated at opposite ends against the spider 78 andthe plunger 64. As will presently appear, the strength of the spring 98is coordinated with the control structure used in the improved pump toprovide exceptional operating efficiency.

Foreign particles are filtered from the fuel flow through the pump in anextremely efficient manner which avoids interference with the outputeiciency of the pump even after the accumulation of matter filtered fromthe fuel has become substantial.

For this purpose a hollow cylindrical filter 100, Fig. l, having adiameter approximately equal to that of the solenoid assembly 18, isdisposed in surrounding spaced relation to the intake valve assembly 66.One end of the lter 100 abuttingly engages the peripheral edge of theretainer 52. The other end of the filter 100 extends a substantialdistance beyond both the body 10 and the intake valve assembly 66. Apressure disc 102 closes the projecting end of the filter 100.

The portion of the filter 100 projecting beyond thc body 10 is encasedwith a filter bonnet or bowl 104. A radial flange 106 on the body end ofthe bonnet 104 fitswithin a shallow counterbore 108 in the adjacent endof the body 10 containing a sealing gasket 110.

The bonnet 104 is releasably held firmly against the gasket 110 by meansof a swingable bail 112 extending across the outer end of the bonnet andhaving opposite ends pivotally supported in diametrically opposed bores114 and 116 formed in the adjacent marginal edge of the body 10.Pressure is applied from the center of the bail 112 to the center of thebonnet 104 by a screw assembly comprising an outwardly convex pressurecup 118 adapted to seat against the center of the bonnet 104, a threadedstem 120 projecting through the cup 118 to engage the bail, and aknurled pressure nut 122 threadedly receiving the stem 120 and abuttingagainst the cup.

It will be noted that a protuberance 124 swaged inwardly from the centerof the bonnet 104 engages the pressure disc 102 to apply sufficientlongitudinal pressure to the filter 100 to form an effective seal aroundopposite ends of the filter.

To gain access to the filter 100 it is necessary merely to turn the nut122 to release pressure on the bonnet 104, swing the bail 112 to oneside, and remove the bonnet 104. The filter 100 can then be lifted offfor replacement or to provide unobstructed access to the previouslydescribed internal components of the pump.

The filter 100 is completely surrounded by a fuel supply chamber 125formed by cylindrical space between the filter and radially outwardstructure of the body 10 and the bonnet 104 and by space between thepressure disc 102 and the bonnet. Fuel is supplied to the chamber 125through an inlet bore 127, Fig. 2, extending radially through themarginal edge of the body 10 which surrounds the body end of the filter100. As illustrated diagrammatically in Fig. 2, the inlet bore 127 isconnected to a suction line 129 extending to a fuel tank 131.

The very large cylindrical area of the porous filter 100 provides, ineffect, for a free flow of fuel through the filter from the supplychamber 12S to the space around the inlet Valve 66. The differentialpressure required to strain fuel through the filter at a high rate isnot sufficient to produce any significant impairment of the operatingefiiciency of the pump even though the overall accumulation on thefilter of foreign material screened from the fuel has becomesubstantial.

Energization of the solenoid 38 is controlled by a readily demountablesnap switch assembly 126 supported on a cylindhical boss 128 integrallyformed on and extending laterally from the outer shell of the body 10.As shown in Fig. l, the boss 128 is aligned along the longitudinal axisof the body 10 with the portion of the barrel element 14 extendinginwardly from the web 16.

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Thesnapswitch 126 is controlled in `response to reverse movements of thepistons 64 by means of a generally vertical lever assembly 130.

The lever assembly 130 is centrally supported by a horizontal pivot pin132 extending across the medial portion of a cartridge 134. Thecartridge 134 is inserted through the centrally open boss 128 and seatedagainst a gasket 136 encircling a radial bore 138 in the adjacent sideof the barrel element 14. The cartridge 134 has an open outer endseparated from an inwardly open inner end by a transverse annulardiaphragm 14d substantially alined with the pivot pin 132. The diaphragm14!) has an inner marginal edge sealed around the medial portion of thelever assembly 30 and an outer marginal edge firmly held and sealedagainst the outer shell of the cartridge 134.

The sealing diaphragm 140 is formed from a tough plastic material whichis substantially unaffected by contact with automotive vehicle fuels andhighly resistant to fatigue by flexure. A preferred material used forthis purpose is tetrafluoroethylene available under the trade nameTeflon from E. i. du Pont de Nemours 8: Co., Inc., Arlington, NewJersey.

The inner end of the lever assembly 13d extends into nn annular groove142 recessed into the outer cylindrical surface of the adjacent end ofthe plunger 64. As shown, the groove 142 extends a substantial distancealong the axis of the plunger 64 between an annular shoulder 144 and anannular abutment 146 on the extreme adjacent end of the plunger.

To soften the action of the abutments 144, 146 on the lever assembly130, as this action is transmitted to the outer end of the leverassembly, the lever assembly is centrally connected together by aresilient coupling 148 which yieldably holds opposite ends of the leverassembly in a predetermined fixed relationship to each other while at thsame time providing for limited bending of the lever assembly at thecoupling.

vFrom the coupling 148, the lever assembly 130 pro jects outwardlythrough the bottom of a cup-shaped switch casing element 150 nested inthe boss 128. Covered by a circular switch support plate 152, the outerend of the switch cup 150 is flanged radially outward. Axial pressure isapplied to the outer periphery of the switch cup 150 through the annularmarginal edge of the plate 152, which is engaged by an annular shoulder156 on a quick disconnect cap 158 forming a domelike cover for the plate152. The cap 158 is retained on the boss 12S by quick thread means. Asshown in Fig. 8, a skirt 166 o-n the cap 150 telescopes around the boss128 and defines two open ended helical slots 162 which receive twoanchoring pins 164 projecting from opposite sides of the boss. it willbe understood that the construction shown in Fig. 8 is duplicated on theother side of the boss 128 and cap 158.

lt is noteworthy that the switch actuating cartridge 134 is insertedthrough the boss 128 ahead of the covered cup 150 and held firmlyagainst the seal 136 by pressure applied, as shown, through an annularwasher 166 inserted between the outer end of the cartridge and theadjacent inner end of the cup.

Electric power for energizing the solenoid 3S is supplied through aninsulated lead wire 170 adapted to interconnect with the positiveterminal of a vehicle battery (hot shown). The wire 170 extends througha central opening 172 in the cap 164 to connect with a positive terminalpost 174 supported at its outer end on the plate 152. As shown in Fig.7, the terminal post 174 extends inwardly into the terminal clip 48,which is connected through the wire 44 to one end of the solenoid 38.

The other terminal clip 46, Fig. 7, connected to the opposite end of thesolenoid 38, receives the inner end of a second terminal post 176parallel to the post 174 and Supported at its outer end on the plate152.

The terminal post 176 and hence the solenoid 38 is controllably groundedthrough the previously mentioned snap switch assembly 126. Since thespeciiic construction of the switch assembly 126 can be varied by thoseskilled in the art, it need not be speciically described here. It issuicient to point out that the terminal post 176, Fig. 7, is connectedto a pair of yieldably supported stationary contacts 17g, Fig. l. Thecontacts 178 oppose a coacting pair of yieldably supported, movablecontacts 18d) grounded through the plate 152.

The contacts 180 are moved into and out of engagement with the contacts178 by an over-center compression spring 132 acting between the contacts180 and a swingable spring support element 184 extending downwardly fromthe plate 152. An apertured lug 186 on the spring support 184 receivesthe upper end of the lever assembly 130. The support element 184 isformed from an insulating material.

The lever assembly 13) moves the spring support element 184 through adead center position 'between one eX- treme position in which the spring182 biases the contacts 1S() into engagement with the contacts 178 andanother extreme position in which the spring 1%2 biases the contacts 130out of engagement with the contacts 178 to break the circuit through thesolenoid 38.

The positional relationship o'r the parts is such that upon opening ofthe switch 126 to deenergize the solenoid 38 the spring 98 moves theplunger 64 to the right, Fig. l, to produce a substantial gap betweenthe inner periphery of the circuit member 52 and the adjacent end of theplunger before the plunger shoulder 144 operates through the switchassembly 131i to close the switch. The solenoid assembly 18 thenoperates as described to magnetically move the plunger 64 in theopposite direction until the plunger shoulder 146 engage the lever 130to effect opening ofthe switch 126 with a snap action. This deenergizesthe solenoid 38 to continue reciprocation oi' the plunger.

Electrically energized reciprocation of the plunger 64 thus provided foris utilized to pump fuel from the pumping chamber 69 to a plenum chamber192 formed at the right hand end of the plunger.

The plenum chamber 192 is dened within the intermediate portion of thebarrel element 14. The lateral `bore 138 opening through the barrelelement 14 is closed by the previously mentioned switch controlcartridge 134. The end of the barrel element 14 opposite the plunger 64is plugged by a fluid ow control assembly 194 to be described presently.

Reciprocation of the plunger 64 pumps iluid from the chamber 69 into theplenum chamber 192 through a cylindrical bore 196, Figs. l and 4,extending longitudinally through the plunger. The bore 196 contains ahighly eiiicient check valve 193 which is practically silent inoperation even when the plunger is reciprocating at a rapid rate toeffect self priming of the pump.

Actually the cylindrical, plunger bore surface (also denoted by thenumeral 196) forms a part of the valve 19S which seals the bore againstreverse flow of iiuid. As shown in Figs. l and 4, sealing of the bore196 against the reverse dow of fluid is effected by engagement with thebore surface of the semi-elliptical edges of a pair of flexible valveblades 206, 262. The base of each blade is just sufficiently lwide toextend transversely across the bore 196. As shown, each blade 213i?, 292extends from its base toward the plenum chamber end of the bore 196 andhas a length approxi-mately twice the diameter of the bore.

The bases of the two blades 209 and 292 are integrally joined togetherand clamped between two narrow, opposing supports 266 and 208 extendingtransversely across the bore 1%. The two supports 2ti6 and 20S joinrespectively at opposite ends with two clamping rings 210 and 212inserted into a counterbore 214 in the intake valve end of the plunger64. A cylindrical retaining ring 216 pressed into the counterbore 214holds the rings rrnly in place against the bottom of the counterbore.

Both blades 200, 202 are formed from a single fiat section of a firm yetflexible plastic material, preferably tetrauoroethylene, which will bereferred to by the pre` viously mentioned trade name Teonf l Integrallyformed from the same piece of material, the blades 200 and 202 tend tostraighten out with respect to each other to engage the marginal edge ofeach blade with the cylindrical bore surface 196. The semi-ellipticalshaping of each blade permits the blade to remain substantially at whileeffecting an engagement between the marginal edge of the blade and thebore surface 196 which is continuous around the blade as it projectsfrom its supported base. Moreover, the marginal edge of each blade-see,for example, the edge 218 of the blade 200, Fig. 4--is shaped to makesurface rather than line contact with the bore surface 196.

In operation, only slight differential fluid pressure tending to producefluid flow through the bore 196 toward the plenum chamber causes the twovalve blades 200, 202 to swing together. This allows substantiallyunrestricted laminar flow of fluid through the bore. Resistance to theflow of fluid through the valve 198 is minimized not only by the largeunobstructed flow areas around the supports 206, 208 and along thelblades but also by the fact that the fluid passes by the valve andthrough the bore 196 in a laminar flow pattern without changingdirection.

Reverse fiow of tiuid through the bore 196 is prevented by the blades200, 202 swinging outwardly to seal against the bore surface 196 in themanner described. Differential pressure tending to produce a reverseflow of uid past the valve serves to increase the pressure With whichthe edges ot' the blades 200, 202 are sealed against the bore surface.

Constructed in the manner described, the valve 198 is virtuallysoundless in operation.

This noiseless operation of the valve 198 is particularly significant inquieting operation of the pump even when the plunger 64 is reciprocatedat the exceptionally high rates prevailing when the pump is pumping airand fuel vapor in a self-priming phase of its operation.

The free iiow characteristics of the unidirectional valve 198facilitates quick movement of the plunger 64 toward the intake valveassembly 66 to successively recock the power spring 98. The ability ofthe plunger 64 to move quickly toward the intake valve is highlyadvantageous. lt minimizes the period during which the actuatingsolenoid 3S must be energized, with consequent reductions in the powerconsumption of the pump. Also, it minimizes interruption in themaintenance of normal pumping pressure in the plenum chamber 192.

The effective volumetric output of the pump from the pumping chamber 192is controlled in accordance with the back pressure on the pump by meansof a regulator, including the previously mentioned assembly 194, whichserves the additional function of assuring an even pump output pressurethat can be adjusted to different pressure levels to fulfill the fluidpressure requirements of different internal combustion enginecarburetors.

The regulator valve assembly 194 operates to throttle fluid underpressure from the plenum chamber 192 into a discharge chamber 220 formedin the adjacent end of the body around and extending beyond the outerend of the barrel element 14. The outer end of the discharge chamber224i is closed by a flexible diaphragm 222 also formed fromtetrafluoroethylene. The peripheral edge of the diaphragm 222 is securedto the `adjacent marginal edge of the body 10 by the peripheral edge ofa header disc 224 detachably secured to the body by screws 226. A11outlet from the discharge chamber 220 is provided by a radial bore 228,Fig. 3, extending through the adjacent marginal edge of the body shell10. As shown diagrammatically in Fig. 3, the bore 228 connects with afuel line 229 extending to an internal combustion engine earburetor 231.

Structurally, the regulator valvei assembly 194 comprises an outwardlyopen cup 230, Figs. 1 and 6, threaded into the outer end of the barrelelement 14. Two openings 232 in the bottom 234, Fig. 6, of the cup 230provide communication between the pumping chamber 192 and the interiorof the cup.

A centrally bored annulus 236 pressed into the outer end of the cup 230defines an annular valve seat 238 opposing a circular valve member 240urged toward the seat by a compression spring 242 supported by the cupbottom 234. A cylindrical skirt 244 on the valve member 240 encircles acylindrical guide 246 staked to the cup bottom 234.

The inner diameter of the valve member skirt 244 is dimensioned toprovide radial clearance around the cylindrical guide 246 justsufficient to provide an effective dashpot action which steadiesmovement of the valve member 240 toward and away from the seat 238.

The valve member 240 is moved away from the seat 238 against the spring242 by means of a stem 248 cxtending from the valve member through theannulus 236 to engage the center of the diaphragm 222.

The central portion of the diaphragm 222 is backed up on the sideopposite the valve assembly 194 by a circular support or pressuredistribution head 250. A stem 252 fixed to the side of the pressure head250 opposite the diaphragm 222 extends into a helical compression spring254 seated Within an inwardly open bore 256 in a pressure regulatingscrew 258. The screw 258 is threaded into a central spud 259 on theheader plate 224 and held in adjusted position by a locknut 260.

The pressure control spring 254 acts through the head 250 and diaphragm222 to hold the valve member 240 in open position until the backpressure on the pump, i. e., the pressure within the discharge chamber220, has reached a predetermined value sufficient to meet the fuelpressure requirements of the carburetor 231. When this back pressure,which is practically synonymous with the effective output pressure ofthe pump, reaches the predetermined value the pressure of fuel on thediaphragm 222 overcomes the force of the spring 254 allowing the spring242 to move the valve member 240 toward the seat 238.

The back pressure required to effect closing of the regulating valve inthis manner can be readily adjusted to meet the fuel pressurerequirements of different carburetors by adjusting the threaded screw253 to vary the residual stress in the spring 254.

it is significant that in addition to its function in serving as acontrol for the throttling valve member 240 the diaphragm 222 provideseffective assurance of an even output pressure from the dischargechamber 220. Thus, as shown, the pressure head 250 terminates asubstantial'distance radially inward of the adjacent marginal edge ofthe body 10, thus leaving an annular portion 262 of the diaphragmunsupported by the pressure head. Due to the flexibility of the materialforming the diaphragm 222, the unsupported annular portion 262 pulsatesto effectively suppress rapid pressure fluctuations which mightotherwise occur in the discharge chamber 220. As a result, the outputpressure from the chamber 220 is maintained at a substantially evenlevel.

lt may be observed that the plunger 64 could have a tendency toover-travel when it is cycling at an accelerated rate during a pumppriming phase of its operation. This is effectively controlled by meansof a buffer spring 264, Fig. l, supported in a counterbore 266 in theplenum chamber end of the plunger 64 and projecting outwardly beyond theplunger to engage the bottom of the valve cup 230.

The improved pump thus formed has extraordinary efficiency in operationwhich provides not only for highly significant minimiation of'the sizeand weight of the pump structure but also for strikingly sharpresponsiveness of the pump to only a slight diminution in the normalback pressure in the pump discharge chamber 220 to pump fuel at a highrate sutiicient to meet the requirements oi even the most powerfulengines used in automotive vehicles. The automatically controlledthrottling action of the regulator valve assembly 194 limits thepressure in the discharge chamber 220 to a predetermined value which canbe tolerated by the carburetor 231, while at the same time providing forthe use of a powerful plunger operating spring 93 that enables the pumpto meet extremely high volumetric output requirements by means ofpumping structure of reduced overall size and weight. The extraordinaryresponsiveness of the pumping action to even a slight diminution in thenormal back pressure in the discharge chamber 220 is such that thedischarge of fuel from the pump at a rate sufiicient to supply acarburetor of even the most powerful automotive vehicle engine does notresult in an undesirable drop in pressure at the pump outlet 228, Fig.3.

To briefly review the extraordinary serviceability of the pump thusprovided, it will be appreciated that every major component of the pumpis readily accessible for inspection or repair in the event this becomesdesirable. The switch E26 can be quickly removed simply by turning thecap iSd to release the latter from the boss 128. After lifting theswitch 126 and cup 15) out of the boss M3, the service man can lift outthe lever 133 and cartridge 134.

Removal or" the screw attached header 224 provides free access not onlyto the diaphragm 222 and its spring support structure but, also, to thethrottling valve assembly 194, which can be quickly unthreaded from thebarrel element 14.

Turning of the nut 122 at the opposite end of the pump releases the bail112 in the manner described, thus affording convenient access to thefilter 160 and intake valve assembly 66. The assembly 66 can be screwedout orr the boss 68 to permit withdrawal of the spring 93 and plunger 64if desired. Further, the rerainer 52 can be screwed out of thecounterbore 54 to permit the remaining components of the solenoidassembly 18 to be slid off the tube 29 and out of the body 10.

The readiness with which access may be had to the component structure ofthe pump adds much in the way of the overall utility to the operationalcapabilities afforded by the invention.

l claim:

l. For supplying fuel to an internal combustion engine carburetor, ahigh capacity fuel pump comprising, in combination, a` reciprocablemagnetic plunger, means including one end of said plunger defining aplenum chamber, means including the opposite end of said plungerdefining a pumping chamber, means including a fuel intake check valveconnected to supply fuel to said pumping chamber, a solenoid operatingassembly including two spaced circuit members disposed in adjacentrela-tion to said plunger to urge the latter magnetically toward anoverlapping position with respect to both circuit members, a powerfuloperating spring connected to said plunger to urge the latter away fromsaid position in a direction for expanding said pumping chamber, saidplunger defining a passageway extending therethrough between saidpumping chamber and said plenum chamber, a check valve mounted on saidplunger to prevent reverse tlow of liuid through said passageway towardthe pumping chamber end thereof, electric power supply means connectedto said solenoid assembly and mounted in association with said plungerto energize the solenoid assembly as an incident to predetermined springproduced movement of the plunger toward said plenum chamber and todeenergize the solenoid assembly as an incident to predeterminedmagnetically produced movement of the kplunger foward Seid pumpingchamber, means d ening a fuel discharge chamber and including yieldablemeans preconditioned to move reversibly in response to changing iiuidpressure within the discharge chamber, a control valve connecting saidplenum chamber to said discharge chamber, and means coacting with saidcontrol valve and with said yieldable discharge chamber defining meansto effect closing of the control valve as an incident to movement ofsaid yieldable means by an increase in pressure within said dischargechamber to a` predetermined value and to quickly open the control valveas an incident to movement of said yieldable means in response to aslight decrease in the discharge chamber pressure below saidpredetermined value.

2, For maintaining a continuously adequate supply of `fuel to a highpowered internal combustion engine carburetor, a compact high capacityelectric fuel pump comprising, in combination, a body including anelongated outer shell and a hollow barrel element generally concentricwith the outer shell, a nonmagnetic guide tube projecting from one endof said barrel element generally along the axis of elongation of saidbody shell and dis posed substantially within said shell, a solenoidslidably encircling said tube, magnetic circuit means for said solenoidincluding two annular discs detachably encircling said tube at oppositeends of the solenoid, the disc remote from said barrel element forming aretainer detachably secured to said body shell, a fuel intake valveassembly threadedly secured in said retainer disc in covering relationto the adjacent end of said tube, a` magnetic plunger slidably disposedwithin said tube for recprocation therein, a strong power springinserted between said intake valve assembly and the adjacent end of saidplunger to urge the latter away from said retainer disc, said plungerdefining a bore extending longitudinally therethrough, a check valvemounted on said plunger to prevent reverse iiow of fiuid through saidplunger bore toward said intake valve assembly end thereof, said barrelelement defining an opening in the side thereof, a switch actuatingcartridge removably disposed in sealing relation to said opening andcontaining a. transverse sealing diaphragm in the cartridge, a switchactuating lever assembly pivotally supported on said cartridge andextending into coacting relation with the adjacent end of said plunger`for actuation by movement of the latter in opposite directions, saidbody shell defining a hollow `boss thereon aligned with said actuatorcartridge to permit ready insertion and removal of the latter throughthe boss, a control switch assembly shaped to fit removably into saidboss for coaction with said switch actuator, said switch assemblyincluding terminal posts extending inwardly, terminal sockets connectedwith said solenoid and supported on said annular solenoid circuit discadjacent said barrel element in position to re eive said terminal posts,a quick disconnect cap disposed in covering relation to said boss andshaped to apply retaining force to said switch assembly, a control valveassembly detachably secured in the end of said barrel element oppositesaid solenoid whereby said barrel element is closed oft to form a plenumchamber therein, means on said body adjacent said control valvecooperating with the body to define therewith a discharge chambercommunicating with the downstream side of said control valve, saiddischarge chamber defining means including pressure responsive meanspositioned to operate in response to changes in fluid pressure withinsaid discharge chamber, means coacting with said pressure responsivemeans and with said control Valve to close the latter automatically inrespouse to a. buildup in pressure within said discharge chamber to apredetermined carburetor supplying level and to open said control valveautomatically in response to a receding in the discharge chamberpressure below said level, and means defining an outlet from saidydischarge chamber.

3. For providing a high powered internal combustion engine carburetorwith a continuously adequate supply 11 t Y of fuel under properpressure, a compact high capacity fuel pump comprising, in combination,a reciprocable magnetic pump plunger, meansY supporting said plunger forrecipi'ocation and forming an effective fluid seal therearound, meansincluding one end of said plunger defining a plenum chamber, and meansincluding the other end of said plunger Vdefining a pumping chamber',means including a fuel intake check valve connected to supply fuel tosaid pumping chamber, said plunger defining a bore extendingtherethrough between said pumping chamber and said plenum chamber, acheck valve mounted on said plunger in position to automatically blockfluid flow through said bore toward the pumping chamber end thereof, astrong power spring inter'- connected With said plunger to urge thelatter in a direction to contract said plenum chamber, said pow-crspring vhaving great effective strength relative to the effectivepressure area of the plenum chamber end of said plunger to produce anexcessive fluid pressure within said plenum chamber, a solenoid assemblypositioned in relation to said plunger to operate upon energization ofthe solenoid assembly to magnetically force the plunger against theaction of said power spring a substantial distance in a direction tocontract said pumping chamber, means for controlling energization ofsaid solenoid assembly in response to movement of said plunger inopposite directions, means defining a discharge chamber adjacent saidplenum chamber, a control valve connecting said plenum chamber with saiddischarge chamber, said discharge chamber defining means including amovable element exposed to fluid pressure within the discharge chamber,resilient means coacting with said movable element to urge the latter ina direction for contracting said discharge chamber, said resilient meanshaving an effective strength such that the fluid pressure within saiddischarge chamber' required to move said movable element through apredetermined positional range closely approaches a predeterminedcarburetor pressure, and means interconnecting said control valve withsaid movable element to effect opening and closing of said valve as anincident to reverse movements of said element through said predeterminedrange thereof.

4. For maintaining a continuously adequate supply of fuel to a highpowered internal combustion engine carburetor, a compact highlyefficient electric fuel pump capable of producing an even outputpressure readily adjustable to different values, said pump comprising,in combination, a hollow body, an elongated plunger formed of magneticmaterial, means on said body supporting said plunger for reciprocationand forming an effective fluid seal tlierearound, means including oneend of said plunger defining a plenum chamber within said body, meansincluding the other cnd of said plunger defining a pumping chamber,fluid supply means including an inlet check valve connected to supplyfuel to said pumping chamber, said plunger defining a bore extendingtherethrough between said chambers at opposite ends thereof, a checkvalve mounted on said plunger to automatically prevent flow of fluidthrough said bore toward the pumping chamber end thereof, a strong powerspring coacting with said plunger to urge the latter in a direction forcontracting said plenum chamber, a solenoid assembly positioned inrelation to said plunger to operate upon energization the solenoidassembly to magnetically move said plunger against said spring in adirection for contracting said pumping chamber', a removable switchmounted on said body and connected to energize said `solenoid assembly,removable actuating means for said switch coacting with said plunger toclose said switch as an incident to movement of the plunger by saidspring to a predetermined position and to open said switch as anincident to predetermined movement of the plunger by the solenoidassembly to a second predetermined position, means on said body coactingtherewith to define a discharge adjacent said plenum chamber', a controlvalve connecting said plenum chamber with said discharge chamber, saiddischarge chamber defining means including a flexible diaphragmsupported at the peripheral edge thereof, a support head engaging thecentral portion of said diaphragm on the side thereof opposite from saiddischarge chamber, the outer' periphery of said support head terminatinga substantial distance radially short of the supported peripheral edgeof said diaphragm thus leaving an annular' portion of said diaphragmaround said head free to pulsate to absorb pressure fluctuations withinsaid discharge chamber, spring means operating on said head to urge saiddiaphragm in a direction to contract said discharge chamber, adjustingmeans coacting with said head spring means to regulate the residualforce thereof thereby controlling the carburetor supplyingv fluidpressure with said discharge chamber required to move said diaphragmthrough a predetermined positional range, means connected between saiddiaphragm and said control valve to effect opening and closing of saidvalve as an incident to movement of the diaphragm in opposite directionsthrough said predetermined positional range, and said plunger powerspring having a strength related to the effective pressure area of theplenum chamber end of the plunger such that the maximum spring pressureexerted on fluid within said plenum chamber is greatly in excess of thedischarge chamber fluid pressure required to move said diaphragm toeffect closing of said control valve.

5. A compact high capacity electric fuel pump comprising, incombination, a body including a hollow shell, an elongated magneticplunger, means supporting said plunger within said body shell forreciprocation and forming an effective fluid seal around the plunger,means including one end of said plunger defining a plenum chamber, meansincluding the opposite end of said plunger and a fuel intake check valvedefining a pumping chamber, a strong power spring interconnected withsaid plunger to urge the latter in a direction for contacting saidplenum chamber, a solenoid assembly positioned in relation to saidplunger supporting means to operate upon energization of the solenoidassembly to magnetically force the plunger against said power springtherefor in a direction for contracting said pumping chamber, switchmeans connected to controllably energize said solenoid assembly, switchcontrol means coacting with said switch means and with said plunger toenergize and deenergize said solenoid in response to movement of saidplunger respectively toward and away from said plenum chamber, saidplunger defining a cylindrical bore extending therethrough between saidpumping chamber and said plenum chamber, narrow valve support meansmounted on said plunger and extending diametrically across said boretherein, a pair of flexible check valve blades disposed within saidplunger' bore and supported at the base of each blade by said valvesupport means, each blade having a maximum length perpendicular to saidvalve support means substantially greater than the radius of saidplunger bore and extending from said valve support means toward theplenum chamber end of said bore, the marginal edge of each blade awayfrom said valve support means having a generally semi-elliptical shapeto seal against the adjacent cylindrical surface of said plunger bore inresponse to differential fluid pressure across said blades tending toproduce fluid flow toward the pumping chamber end of said bore, saidplenum chamber defining means including a control valve for releasingfluid therefrom, means including a fluid pressure responsive actuatormounted on said body to define therewith a discharge chamber adjacentsaid plenum chamber' and communicating directly with the discharge sideof said control valve, means interconnecting said fluid pressureresponsive actuator with said control valve to effect closing of thelatter' automatically in response to a build-up in pressure in saiddischarge chamber to a predetermined carburetor' supplying pressure,said power spring for said plunger havinga predetermined strength inrelation to the effective pressure area of the plenum chamber end of theplunger to produce within said plenum chamber a maximum Huid pressuregreatly in excess of the iiuid pressure required in said dischargechamber to effect closing of said control valve by means of saidpressure responsive actuator therefor, and means dening an outlet fromsaid discharge chamber.

6. For maintaining a continuously adequate supply of fuel to a highpowered internal combustion engine carburetor, a readily serviceableelectric fuel pump comprising, in combination, a body including anelongated outer shell and a hollow barrel element having an inner enddisposed within the medial portion of the shell, a nonmetallic guidetube extending from said inner end of said barrel element along the axisof said shell, a solenoid slidably encircling said tube, magneticcircuit means for said solenoid including a magnetic disc encirclingsaid tube at the inner end of said barrel element and an annularmagnetic retainer detachably secured to said'body shell and encirclingthe end of said tube remote from said barrel element, a magnetic plungerslidably disposed within said tube, an intake check valve assemblydetach- `ably mounted on said retainer in covering relation to theadjacent end of said tube whereby a pumping chamber is defined betweensaid intake valve assembly and the adjacent end of said plunger, astrong power spring interposed between said intake valve assembly andthe adjacent end of said plunger to urge the latter away from saidmagnetic retainer, a hollow cylindrical strainer removably seated inencircling relation to said intake `valve assembly, said strainer beingsubstantially coaxial to said tube and having a diameter approximatelyequal to that of said solenoid, a strainer bonnet covering the end ofsaid strainer remote from said retainer, quick release means detachablyholding said bonnet in sealed relation to said body shell, means forsupplying fuel into surrounding relation to said strainer, a controlvalve removably secured in the end of said barrel element opposite saidsolenoid, the intermediate portion of said barrel element defining aplenum chamber, removable switch actuating means extending into theplenum chamber portion of said barrel element and forming a sealtherewith, said switch actuating means coacting with said plunger foractuation by movement of the latter in opposite directions, said bodyshell defining a hollow boss substantially alined with said switchactuating means, a quickly removable switch seated in said boss andcoacting with said actuating means `for operation thereby, separablemeans connecting said switch with said solenoid, a quick disconnect capmounted in covering relation to said boss to hold said switch in seatedposition therein, said plunger defining a bore extending therethroughbetween said pumping chamber and -said plenum chamber, a check valvemounted on said plunger to prevent reverse flow of fluid through saidbore `toward said pumping chamber end thereof, movable pressureresponsive means attached rto the end of said body opposite saidstrainer end thereof to define with the body a discharge chambercommunicating with the outlet of said control valve, means for closingsaid control valve in -response to movement of said pressure responsivemeans by ypredetermined carburetor supplying fluid pressure -within saiddischarge chamber, said plunger power spring having an effectivestrength related to the pressure area of the plenum chamber end of saidplunger to produce fluid pressure within said plenum chamber greatly inexcess of the fluid pressure required in said discharge chamber foractuating said pressure responsive means to close 'said control valve,and means forming a fluid outlet from said discharge chamber.

47. ln an electric fuel pump, the combination of an elongated magneticplunger, means supporting said plunger for reciprocation and forming aneffective fluid seal'therearound, means defining a plenum chamber at oneend o'f said plunger, means including a fuel intake valve defining apumping chamber at the other end of said plunger, said plunger defininga bore extending longitudinally therethrough between said pumpingchamber and said plenum chamber, narrow check Valve support meansmounted on said plunger and extending diametrically across said boretherein a substantial distance from the plenum chamber end of the bore,two exible valve blades each having a base thereof anchored to saidvalve support means, said blades being formed of a plastic materialhighly resistant to petroleum fuels, each of said blades extending fromsaid support means therefor toward the plenum chamber end of said boreand having a peripheral edge shaped to separably seal against theadjacent surface of the bore, a strong power spring coacting with saidplunger to urge the latter in a direction to expand said pumpingchamber, solenoid means positioned in relation to said plunger tomagnetically move the latter against the force of said spring in adirection for contracting said pumping chamber, and control meansconnected with said solenoid means and coacting with said plunger tocontrol said solenoid means in response to reverse movements of saidplunger.

8. For maintaining to a high powered internal combustion enginecarburetor an adequate supply of fuel at au even adjustable pressure, acompact high capacity electric fuel pump comprising, in combination, amagnetic plunger, means supporting said plunger for reciprocation anddefining an effective fuel seal therearound, means including a fuelintake valve defining a pumping chamber at one end of said plunger, saidplunger defining a bore extending therethrough from said pumpingchamber, a check valve mounted on said plunger to prevent reverse flowof fluid through said bore toward said pumping chamber end thereof, astrong power spring coacting with said plunger to urge the latter in adirection to expand said pumping chamber, solenoid means positioned inrelation to said plunger to magnetically urge the latter against saidspring therefor in a direction for contracting said pumping chamber,switch means coacting with said plunger and connected with said solenoidto control energization of the latter in response to reverse movementsof the plunger, means including a control valve assembly defining aplenum chamber at the end of said plunger opposite said pumping chamber,said control valve assembly including a valve seat, a movable valvemember disposed in opposing relation to said seat, a cylindrical guideskirt on said movable valve member, a guide stem extending into saidskirt to guide and hydraulically check movement of the valve membertoward and away from said valve seat, means including a flexiblediaphragm defining a discharge chamber communicating with the downstreamside of said control valve assembly. stationary means supporting themarginal edge of said diaphragm, a movable support head engaging thecentral portion of said diaphragm on the side thereof opposite saiddischarge chamber, the peripheral edge of said support head terminatinglradially short of the supported marginal edge of said diaphragm toleave an annular portion of said diaphragm unsupported to pulsate toabsorb incipient pressure iiuctuations within said discharge chamber,pressure control spring means coacting with said support head to urgethe latter in a direction for contracting said discharge chamber,adjustable means positioned to regulate the residual stress in saidpressure control spring means, means positioned to transmit reversemovements of the head supported portion of said diaphragm to saidmovable control valve member to effect movement of the latter toward andaway from the coacting valve seat in response to reverse movements ofthe head supported .portion of the diaphragm, and means defining a iiuidoutlet from said discharge chamber.

9. For providing to a high powered internal combustion engine carburetora clean continuously adequate supply of fuel under proper pressure, acompact highly efficient-electric fuel pump comprising, in combination,an elongated body shell, an elongated magnetic plunger, means supportingsaid plunger for reciprocation within said shell and forming aneffective fiuid seal around the plunger, means including a detachableintake valve assembly defining a pumping chamber at one end of saidplunger, said intake valve assembly including a fuel inlet bore therein,a permanently magnetized wire shaped to clamp on said valve assembly andhaving opposite ends shaped to extend across said intake valve bore andmagnetized to collect magnetic particles from fuel flowing through thebore, a strong power spring interposed between said intake valveassembly and said plunger to urge the latter in a direction to expandsaid pumping chamber, a solenoid assembly detachably mounted within saidshell in position to urge said plunger against said spring in adirection for contracting said pumping chamber, a hollow cylindricalfilter removably seated in surrounding relation to said intake valveassembly, a covering bonnet for said filter, quick disconnect meanssupporting said bonnet on said shell in housing relation to said filter,means defining a fuel inlet communicating with the outer surface of saidfilter, said plunger defining a bore extending therethrough from saidpumping chamber, a check valve supported on said plunger to preventreverse fiow of fluid through said plunger bore toward the intake valveassembly end thereof, means defining a plenum chamber at the end of saidplunger opposite said pumping chamber, and solenoid control meansconnected with said solenoid assembly and coacting with said plunger tocontrol energization of the solenoid assembly in response to movement ofthe plunger in opposite directions.

l0. For supplying the large and sharply varying fuel requirements of ahigh powered internal combustion engine carburetor, a self-containedfuel pump having an output pressure highly stabilized continuously at alimited pressure level and comprising, in combination, means defining apumping chamber and including as a component thereof a reciprocablepumping element movable in opposite directions to expand and contractthe pumping chamber, a fuel inlet check valve communicating at thedownstream side thereof with said pumping chamber, means including acomponent portion of said pumping chamber means and defining a plenumchamber immediately adjacent said pumping chamber, a check valve mountedbetween said pumping and plenum chambers on said component portion ofsaid pumping chamber means and having an upstream side communicatingdirectly with said pumping chamber and a downstream side communicatingdirectly with said plenum chamber, means including a component portionof said plenum chamber means and defining a fuel discharge chamberimmediately adjacent said plenum chamber, a control valve mountedbetween said plenum and discharge chambers on said component portion ofsaid plenum chamber means and having an upstream end communicatingdirectly with said plenum chamber and a downstream end communicatingdirectly with said discharge chamber, said discharge chamber definingmeans including as a component thereof a movable chamber expanding andcontracting element spring biased with a yieldable force which moves theexpanding and contracting element in a discharge chamber contractingdirection against internal discharge chamber pressures less than apredetermined limited value and which allows discharge chamber pressuresgreater than said predetermined valve to move the expanding andcontracting element in a discharge chamber expanding direction, meanscoacting with said expanding and contracting element and with saidcontrol valve to effect opening and closing of the latter by movement ofsaid expanding and contracting element in chamber contracting andexpanding directions respectively, a damper connected to said controlvalve to steady opening and closing movements thereof,

reciprocating means coacting with said reciprocable pumping element andincluding a powerful spring connected with said pumping element to urgethe latter in one direction and including externally energized powermeans coacting with the pumping element to intermittently move thelatter in the opposite direction against said spring, and saidreciprocating means having sufiicient strength to pump into the plenumchamber a maximum pressure greatly in excess of said predeterminedlimited value and being yieldable against a plenum chamber pressure inexcess of said maximum pressure.

ll. ln a fuel pump of the type in which a piston is reciprocated in acylinder by an electro-magnet and by a return spring engaging the pistonto pump fuel from a pumping chamber to a second chamber to which anoutlet is connected and in which inlet and check valves are provided forpreventing reverse flow of fuel through the pump, wherein the pump ischaracterized by: the piston return spring being oversized; a thirdchamber integral with the pump, disposed immediately adjacent the secondchamber, and interposed between the second chamber and the outlet; arelatively unrestricted passageway interconnecting the second chamberwith the third chamber to provide substantially no line pressure dropbetween the chambers; a third valve disposed in the passageway; ingelement in first and second opposite directions to and an elasticelement in the third chamber operatively connected to the third valvefor reducing and regulating the pressure of the fuel flowing from thesecond chamber into the third chamber, thereby to provide a highcapacity, 'fast response pump characteristic.

12. For supplying fuel to an internal combustion engine, a high capacityconstant pressure fuel pump comprising a reciprocable pumping element;means including one surface of said pumping element defining a pumpingchamber; a first and second power means for urging said pumping elementin first and second opposite directions to respectively draw fuel intosaid pumping chamber under vacuum and to force fuel from said pumpingchamber under pressure; one of said power means operated by an externalsource of power, the other comprising an oversized power spring inoperative engagement with the pumping element and capable of producing aforce substantially in excess of that required for desired fuel pumpdischarge pressures; the power means causing discharge of fuel from thepumping chamber being elastic and capable of producing a fuel dischargepressure substantially greater than desired fuel pump output pressures;inlet and outlet check valve means for said pumping chamber; meansintegral with the pump immediately adjacent said pumping chamber anddirectly connected therewith defining a plenum chamber; said outletcheck valve interposed between said plenum chamber and said pumpingchamber; means integral with the pump immediately adjacent said plenumchamber and directly connected therewith defining a fuel dischargechamber including a yieldable element preconditioned to move reversiblyin response to changing fluid pressure within the discharge chamber; acontrol valve'interposed between said plenum chamber and said dischargechamber; and linkage connecting the control valve and the yieldableelement for urging the control valve toward closed position incident tomovement of the yieldable element by an increasing pressure within saiddischarge chamber to a predetermined value and urging the control valvetoward open position incident to movement of said yieldable element by aslight decrease in the discharge chamber pressure below saidpredetermined value.

13. A fuel pump for supplying the large and sharply varying fuelrequirements of a high pressure internal combustion engine carburetorcomprising; a pumping chamber; a plenum chamber communicating with oneside of the pumping chamber; a fuel inlet communicating with the otherside of the pumping chamber; a reciprocable element in the pumpingchamber and inlet and outlet 18 the plenum chamber to permitsubstantially no line pressure drop between the chambers; a third valvedisposed in the passageway; and an elastic element in the third chamberconnected to the third valve for reducing and regulating the pressure ofthe fuel flowing from the plenum chamber into the third chamber.

References Cited in the file of this patent UNITED STATES PATENTSWhitted May 9, 1933 Miller Feb. 8, 1949 UNITED STATES PATENT OFFICECERTIFICATE 0F CORRECTION Patent No 2, 872, 871

.Arthur Cu, Allen It is herebjr certified that error appears intheprinted specification of the above numbered patent requiringcorrection and that the said Letters Patent should read as correctedbelow.

Column 5, line 65, for n(hot shown)H read m- (not, shown) column lo,

linel 26, strike out "ing element in first and second oppositedirections to'h1 Signed .and sealed this llth day of August 1959 (SEAL)Attest:

KARL ,Ht

ROBERT C. WATSON Attesting Oficer Commissioner of Patents February lO1959

